Sound film printing



Sept. 8, 1942. D. o. LANDIS SOUND FILM PRINTING Filed Dec. 28, 1940 11 NEG.

. Snuentor Dantel O.Lan

IIIIIII MOTOR I Patented Sept. 8, 1942 Daniel 0.11pm, Upper Darby, 1a., assignor a Radio Corporation America, a corporation Application December 28, 1940, Serial No. 372,095

4 7 Claims. (Cl. '95-'15) This invention relates to the printing of photographic sound record films and, more particularly, to the contact printing of sound records from negatives of the motion picture type onto positives of the motion picture type, and involves a new method, apparatus and product.

One of the difficulties heretofore encountered in the production of talking motion pictures of the sound-on-film type has been the presence of 96-cycle flutter, which has been caused in various ways. Irregularities in sprocket teeth in either the recorder or reproducer will produce,

such flutter and, this has, to a certain extent, been filtered out. However, even when a sound record is made on a recorder which has no sprockets, and is printed on a printer which has no sprockets, and is reproduced on a reproducer which also has nosprocket, a certain amount of 96-cycle flutter persists in films having the usual number of perforations. Since this flutter corresponds to the sprocket-hole frequency, it would seem that the mere presence of the sprocket holes in the film causes some type of distortion or strain in the film itself, or possibly causes some effect during the liquid treatment of the film, the development, and the other attendant operations which affect the sound track.

I have discovered that similar effects occur in both the negative and the positive film and that, if the negative is printed onto positive film stock with the negative sprocket holes more or less accurately located midway between the positive sprocket holes. the amount of resultant 96-cycle flutter in the positive print is materially decreased.

I have accordingly devised an apparatus for printing from the negative onto the positive film stock with this interrelation of the sprocket holes and without slippage between the contacting surfaces of the films at the printing point.

One object of the invention is to provide an improved sound record film.

Another object of the invention is to provide an improved sound record print.

Another object of the invention is to provide a positive sound record film with a minimum of irregularities at sprocket-hole frequency.

Another object of the invention is to provide an improved printer for printing sound record film.

Another object of the invention is to provide an improved printer for printing sound film synchronized with pictures.

Another object of the invention is to provide an improved method of printing a sound record film.

Other and incidental objects of the invention will be apparent to those skilled in the art from a reading of the following specification and an inspection of the accompanying drawing in which Figure 1 is a schematic elevation of my improved printer in normal printing position,

Figur 2 is an illustration corresponding to Figure 1 but showing the apparatus in the position assumed when the positive film is unusually moist, or when the negative film has more than the usual amount of shrinkage.

Figure 3 is an illustration corresponding to Figure 1 and showing theposition of the parts of the printer when the positive film is unusually dry or shrunken or the negative film has less than the usual amount of shrinkage, and

Figure 4 illustrates a modified form of control apparatus for the printer. Referring first to Fig. 1, which shows the apparatusin its normal position, the sound track negative [0 is fed by the sprocket I I to the drum i2 where light is directed through the film by an appropriate optical system indicated at l3 and provided with an appropriate light source ll.

This film is carried snugly over the drum I! by the sprocket l5 and, from the sprocket it, it is fed over the let-off sprocket I6 to the take-up reel H. The positive film stock I8 is fed over a sprocket l9 which maintains a rather large free loop in the film and then passes between the rollers 30 on the arm 28 to the roller 20 which holds it firmly in contact with the negative film on the drum l2 at the printing point. The positive film It then passes around the sprocket 2| to the let-off sprocket 22 and to the take-up reel 23.

The arm 28 carrying the rollers 30 and the sprockets l5 and II is pivoted at 29, this point being so chosen that tension applied to the film by the sprockets l6 and 22 will have a minimum effect on the arm 28.

The sprocket I5 is integral with a gear 24 which meshes with a similar gear 25 on the sprocket 2!. These two gears serve to maintain the sprocket teeth in any desired predetermined relation.

As pointed out above, I have found it desirable to make the print with the sprocket holesof the in footage at the printing point in order to avoid slippage of the films. This is accomplished in accordance with the principles set forth in Bedford Patent 2,098,371, issued November 9, 1937. It is pointed out in that patent that, if the negative stock is maintained in a uniform position and the positive stock isfiexed one way or the other at the printing point, the positive stock may be caused to pass the printing point at a rate which is either greater or less than that of the negative, as desired. Although that patent describes the application of the principle to a contact printer where the sprocket hole relation is disregarded, it is equally applicable in the present apparatus and the mechanism Just described accomplishes this result while maintaining the sprocket holes in predetermined relation.

The sprockets H and I9 may be gear driven at an appropriate speed such that the negative film ID will normally be fed over the surface of the drum l2 without any appreciable slippage. The sprockets l5 and 2| are driven only by the film, while the sprockets l6 and 22 are over-driven through an appropriate slippable clutch so that they maintain the film between the sprockets l5 and I6 and 2| and 22 under tension at all times.

If the number of sprocket holes of the positive film passing the printing point in a given time exceeds the number of sprocket holes of negative film passing the printing point in the same time, then the sprocket 2| will move downwardly relative to the sprocket l5 due to the fact that these two sprockets are geared together. This will cause the arm 28 to move toward the left as shown considerably exaggerated in Fig. 2, which will bend the film farther around the roller 20. This, as described in the Bedford patent, will cause the positive film to pass the printing point at a slower linear speed, thereby raising the sprocket 2| and restoring the apparatus to equilibrium.

Conversely, if the number of sprocket holes of positive film passing the printing point is less than the number of negative sprocket holes in the same length of time, the sprocket 2| will be raised, moving the arm 28 and the rollers 30 to the right, as shown in Fig. 3, thereby wrapping the positive film around the printing drum |2 over the negative film. This will increase the linear speed of the positive film passing the printing point and permit sprocket 2| to descend.

It will be apparent that the exact median position of the arm 28 shown in Fig. 1 will be maintained only when the positive film has some particular length for a given number of sprocket holes, While if for that same number of sprocket holes the film is shorter, the apparatus will run in equilibrium in a position between that shown in Fig. 1 and that shown in Fig. 2, while if for that same number of sprocket holes the positive stock is longer, it will run in equilibrium in a position between that shown in Fig. l and that shown in Fig. 3.

In the form of the invention shown in Fig. 4, the arm 28 which carries the sprockets l5 and 2| does not, actuate the rollers 30 directly, but instead closes contacts 40 and 4| which control the direction of operation of the motor 42. The speed of operation of the motor may be determined by resistors 43 and 44 and the motor drives an arm 45 carrying the rollers 30 in one direction or the other. An appropriate source of power for the motor such as a battery 41 may be provided and in series with this power source there is preferably provided an interrupter 46 which periodically makes and breaks the circuit. The interrupter 46 may be driven by the film feeding mechanism and serves to prevent overrunning of the motor which might otherwise tend to occur before the mechanism had been restored to equilibrium.

I claim as my invention:

1. A sound film printer including means for maintaining two perforated films in nonslipping contact at the printing point and means for maintaining a predetermined staggered relation betwieezi the perforations of the films at the printing p0 n 2. A sound film printer including means for feeding a negative sound record over a drum at the printing point, means for feeding positive film stock in contact with said negative at the said printing point, and means for adjusting the rate of feed of the positive film to maintain the sprocket holes of the two said films in predetermined noncoincident relation.

3. A sound film printer including a movable arm, a pair of sprockets mounted on said arm. the advancement of the raw film stock rotating one of said sprockets and the advancement of the film from which a print is to be made rotating the other of said sprockets, gears connecting said sprockets, and means carried by said arm for controlling the rate of feed of one of said films with respect to the other of said films past the printing point.

4. A sound film printer including a movable arm, a pair of sprockets mounted on said arm, the advancement of the raw film stock rotating one of said sprockets and the advancement of the film from which a print is to be made rotating the other f said sprockets, gears connecting said sprocketsand means carried by said arm for controlling the rate of feed of one of said films with respect to the other of said films past the printing point for maintaining the films at the printing point with their sprocket holes in predetermined noncoincident relation.

5. A sound film printer including a movable arm, a pair of sprockets mounted on said arm, the advancement of the raw film stock rotating one of said sprockets and the advancement of the film from which a print is to be made rotating the other of said sprockets, gears connecting said sprockets, and means carried by said arm for varying the angle of entrance of one of said films to the film support at the printing point.

6. A sound film printer for printing a perforated positive film from a perforated negative film comprising means for advancing said films at the same speed with respect to the number of perforations in said films, means for automatically maintaining the perforations of one of said films midway between the perforations of the other film at the printing point as the distances between perforations vary in one film with respect to respective distances in the other film, and means for light-impressing said films at said point.

7. A sound film printer for printing a perforated positive film from a perforated negative film comprising means for advancing said films in synchronism with respect to the number of perforations in said film, means for automatically maintaining the perforations of said positive film midway between the perforations of said negative film at the printing point regardless of variations in the distances between respective perforations of the two films, and means for lightimpressing said films at said point.

DANIEL O. LANDIS. 

